Grinding machine



Aug. 21, 1934. H, L, BLOOD GRINDING MACHINE 2 Sheets-Sheet ll Filed April 13 1952 n Q N. RN QQ f Xav Y .d l JNMHMM! Hmx malm MW 4Aug. 21, 1934. H. l., BLOOD 1,970,645

GRINDING MACHINE Filed April 13, 1932 2 Sheets-Sheet 2 Halold L1 Blood M/g/ f 1,970,645 'PMEN'HV OFFICE 1,970,645 GRINDING MACHINE Harold L.`Blood, Worcester, ,w assignor to The Heald Machine Co f Worcester,

Mass., a corporation of Massachusetts Application April 13, 1932, Serial-No. 604,988 11 claims. (ol. 51-50) The present invention relates to grinding machines and incertain of its aspects is applicable to any of the various types of grinding machines. Its lparticular utility, however, is ,in connection with internal grinding machines for 'grinding the internal cylindrical or conical surfaces of sleeves, gears,'bushings and like articles. In the Guild and Burns grinding machine Patent No. 1,830,358, issued November 3, 1931, the grinding wheel is fed transversely at right angles to its axis toward the workpiece to procure successively deeperand deeper cuts in said workpiece until said workpiece reaches the finished size and at the end of the grinding operation the grinding wheel is the original position at the beginning of the grinding operation in order to position the grinding wheel for entry -within the bore of the successivework-piece ,without contacting therewith. In each grinding operation, the wheel is' fed transversely from its original position into engagement with the workpiece at the same rate of speed at which it is fed after the wheel engages the workpiece and begins to cut into said workpiece. The time involved in the transverse feeding of the grinding wheel from its original position until it engages the surfaceof the workpiece, during which time no grinding action takes place, is entirely unproductive and thus the grinding operation -on each workpiece involves more time than would be necessary if positive grinding began immediately upon entry oi the wheel within the bore of the workpiece. It is accordingly the principal object of the present invention to provide for a relatively fast transverse movement of the grinding wheel toward the surface of the workpiece until theNgrinding wheel engages said workpiece with the rate ofmovement substantially diminished when the grinding wheel engages the surface of the workpiece.

The Taylor Patent No. 1,682,673 issued August 28,' 1928, discloses a mechanism by which the rate of movement of the wheel against the surface of the work is diminished during the grinding operation under the. control of thecrossfeed mechanism for the grinding wheel and the Conradson' Patent No. 1,534,302 discloses a different mechlanism by which the rate of feeding movement may be varied during the grinding operation by entry of a gage within the bore of the partly ground workpiece. By .reason of the variations lin size of the workpieces before the grinding operation thereon. these mechanisms b oth of which operate mechanically when the workpiece is partly ground are unsatisfactory in reducingthe rate of. feeding movement of the grinding wheel just as said wheel engages the surface of the workpiece. Accordingly, a furthenobiect of the present, invention is to provide for reduction of the rapid feeding movement of the grinding automatically returned to wheelwhensaid wheel engages the surface of the unfinished workpiece independently of the size of said unfinished workpiece.

In accordance with thefpresentvinvention, the movement of the grinding wheel'toward the surface of the workpiece is procured at a rapid rate untilv the wheel and work are in engagement when, by the energization of a light responsive element actuated by the sparks from the grinding wheel at the instant of contact, the rate of movement of the grinding `wheel toward the workpiece is substantially diminished.

Other and further objects andadvantages of the invention will more fully appear from vthe following description, taken in connection with the accompanying drawings, in which:-

Fig. 1 is a front elevation of a grinding machine embodying the invention.

Fig. 2 is a plan view of the grindingmachine of Fig. 1. 1

` Fig, 3 is an elevation of the crossfeed mechanism, parts being broken away.

4 is a plan view of the crossfeed mechanism.

Fig. 5 is a diagrammatic View showing the relative position offthe grinding wheel, the workpiece, and the light responsive element.

Fig. 6 is a rear elevation of a. portion of the grinding machine showing the mechanism for the crossfeed retraction.

Fig. '7 is a wiring diagram. p Like reference characters refer to like parts in the diiferent figures.

Referring mst to Fig. 1, the machine provides the reciproca'tory table or carriage 1 ordinarily provided in internalgrinding machines. Either the grinding wheel or the workpiece to be ground may be carried by the tablel, with the reciprocai tions-of the latter utilized in either case to produce a relative traversing movement of the grinding wheel over the surface-of the workpiece. In the 4construction shown, the table 1 carries a wheelhead 2 which supports the spindle 3 on which the grinding wheel 4 is mounted, and the work to be operated uponl isv heldin a workhead l5, the latter carried by a bridge 6 which spans the slideways, not shown, providedlfoi` the back and forth movement of the table 1.

The' back and forth movement of the table 1;

to cause the grinding wheel to make the required traverse over the surface of the'workpiece a may be imparted in any suitab e manner as by the use of the fluid pressure-mechanism forming the subject matter .of the Heald and Guild Patent No. 1,582,468, granted April 27, 1926. Itis sumcient to note forthe purposes of the present application that the reciprocations of the table are controlled by the use of spaced adjustable dogs 'I and 8 mounted on the table 1 in a position to engageand move a reversing lever 9, .the latter 12u during the grinding operation being located begrinding wheel in a position to enter the-"borc tween the two Vdogs and being automatically of an unnished workpiece.' To this end, the engaged an'd actuated thereby. v' screw shaft 12 carries on the rearward end there- The crossfeed movement between the workpiece 0f a ratchet wheel 28 which is engaged by a pawl and the grinding wheel to feed said grinding 30, the latter being actuated at the end of a wheel at right angles to its axis against the grinding operation, when the workpiece reaches surface of the workpiece is procured by the mechthe predetermined size, to procure a counterclockanism disclosed in the Taylor Patent No. 1,682,673. wise rotation of the screw shaft 12 (clockwise, as It is sufficientto noteV for the purposes of the viewed from the rear, Fig. 6) to return the grindpresent application that the wheelhead 2 of the ing wheel to the original position which it occumachine, which is mounted on a cross-slide 10, pied at the beginning of the grinding operation. Fig. 2, is-adapted to have a transverse movement Referring now to Fig. 6, the pawl 30 is carried on ways 10 provided by a bracket 11 mounted on on .the end of a bell -crank lever 31 which is the table 1. Movement of the cross-slide is promounted for rotation on the shaft 12 and the cured by rotation of a screw shaft 12, the latter other end of'said lever 31 carries a roller 32 which engaging an internally threaded member secured engages a groove 33 in a horizontal bar 34eleto the cross-slide. The forward end of the screw vation of which, by fluid under pressure-at theshaft 12 carries a ratchet13, and a pawl 14 end of the grinding operation, rotates the bell pivotally mounted on an arm 15, the latter being crank lever 31 to procure turning movement of supported by a stud 16 on the cross-slide, is arthe screw shaft through the pawl 30. Said pawl ranged to engage said ratchet to procure rotation 30 is held out of lengagement with the ratchet of the shaft 12. The arm 15 carries a roller 17 wheel 28 during the crossfeed movement of the which is adapted, at the end of each left hand grinding wheel by a shield 35 carried by an arm' longitudinal stroke of the table l while the grind- 36 secured to the bracket 11, and extending being wheel is in operative positionrelative to the tween said pawl and the ratchet wheel when theI work, to engage a stationary cam 18 carried by bar 34 is in its lower position. a longitudinal bar 20 .attached to the bridge 6. When theA workpiece reaches the predetermined When the roller 17 engages the cam 18, thefarm flnished size, a bell crank lever 37 on the front of 15 is rocked upwardly causing the; pawl 14 to the machine is actuated counterclockwise through engage the ratchet wheel 13, thereby procuring connections responsive to the turning movement a step-by-step clockwise rotation of the ratchet of the crossfeed mechanism, as in the .Taylor wheel and accordingly of the screw shaft 12. Patent No. 1,682,673, or responsive .to entry of `a. During` the upward rocking movement of the gage within the bore of the workpiece, and the arm 15the pawl 14, which is normally held out movement of the lever 37 procures withdrawal of of engagement with the ratchetwheel 13 by the the wheel from the workpiece into the rest pousual spring pressed plunger 2l, is urged into engagement with said ratchet wheel, thereby procuring a clockwise movement of said ratchet wheel. To this end, a depending arm 22, pivot`\ connection between a uid pump,

ally mounted on a stud 23 on the cross-slide, carries, on the lower end thereof,'an` adjustable piri 24 in a position to engage the beveled surface 25 of the pawl 14 as it is moved upwardly to press said pawl against the ratchet wheelisaid pin 24 being adjustable in the arm 22 and being locked in adjusted position by a nut 26.- The lower end of the arm 22 also carries an adjustable screw 27, the -lower end of which, as shown in Fig. 3, engages asurface 28 of the bracket 11, said screw 27-holding the pin 2" in proper position. The rate of, crossfeed movement of the grinding wheel is determined by the position of the arm 22 and the lpin 24 which are normally in the position shown, and said pin, in` accordance'with its location, 'causes the' pawl to procure greater or less angular rotation of the ratchet for each upward movement of thepawl.

Atuthe beginning of the grinding operation, the grinding wheel is moved, from the inoperative position shown, into the bore of the workpiece by the uuid control disclosed-m the aove Hemd and Guild Patent No. 1,582,468, and the crossfecd ovement is procured in response to the reci ''ccations over the surface of the workpiece, ln the manner above pointed out, until the workpiece is reduced to the predetermined nished size when, by suitable mechanism, )as disclosed in the dsition shown, and also procures the retraction of the crossfeed. A depending arm 38 of the bell crank lever 37 moves a valve 40 to provide uid not shown, and the lower end of a cylinder 41 in which a piston is slidable, the latter carrying a piston rod 42 connected to the horizontal bar 34. Admission of iluidunder pressure to the cylinder 41 urges the piston rod 42 upwardly, thereby elevating the horizontal bar 34 to turn the crossfeed screwy 12 for retraction of the crossfeed. The repositioning of vthe grinding wheel or the insertion of an uniinished workpiece within the workhead releases the bell crank lever and permits it to return to its normal position shown, thereby mov ing the valve 40 to the left and providing fluid connection between the cylinder 41 and an exhaust connection, not shown, to permit the bar 34 under its own weight to return toits lower position with the pawl 30 supported outof engagement with the ratchet 28 by the shield 35.

The above described mechanism, of itself, forms no part of the present invention which latter involves the attainment in connection with suchI or similar grinding machine instrumentalities of the'novel and useful objects and results hereinbefore set forth. In accordance with the present invention, as the grinding wheel is moved into l operative position within the bore of the work- Fig. 5, by movement of the table 1 toward 140 piece a, the left, ,said grinding wheel occupies substantially the'position shown in the dotted lines, in

Taylor Patent N0# 1382.673. 0r in the -COnradSOn which position the'surface of the grinding wheel Patent No. i1,534,30'2, above identied, thesgird is entirely out of contact with thefworkpiece. As

ing wheel is withdrawn from the workpiece and run out to the rest position shown to permit the nished workpiece 'to be replaced by an unnnished workpiece within the workhead.

Between successive, grinding' operations .the crossfeed movement is retracted to place the the table 1 is reciprocated to procure a'traverslng. 145 movement ofthe grinding wheel over vthe surface of the workpiece, the pawl 14 is actuated by-the cam 18, as above pointed out, and the ratchet. wheel 13 is rotated to procure arapid crossfeed movement of the, grinding wheel toward the sur- 150 face of the workpiece to diminish the unproductive period of the grinding operation while the` grinding wheel isnot in contact with the workpiece.

As soon as the grinding wheel engages the surface of the workpiece, the crossfeed movement is diminished to the normal crossfeed rate for the grinding operation', such reduction in crossfeed rate being procured independently of the relative position of the cross-slide on the table l. To this end, as the grinding wheel moves into contact with the workpiece, the incandescent sparks caused by the contact of the wheel with the work illuminate a photo-electric cell which procures a decrease in the rate of crossfeed movement. Referring first to Fig. 3, the bracket 11 supports a bell crank lever 43 pivotally mounted on a pin 44 with one end 45 of the lever in a position to engage beneath the end of the adjusting screw 27' when said lever 43 is rocked counterclockwise. The opposite end 46 of the bell crank lever 43 is connected to the armature 47 of a solenoid 48 mounted on the bracket 11, and said solenoid, when energized, procures counterclockwise rotation of the lever 43 to move the end 45 of said lever into position beneath the end of the screw 27 and spacing the pin 24 away from the ratchet wheel 13 so that the pawl 14 engages said ratchet wheel 13 during a shorter portion of its upward movement, and the ratchet wheel is accordingly turned through a smaller angle.

Referring now to Fig. 7, the photo-electric cell or other light responsive instrumentality in a shield 50, which instrumentality is activated by the incandescent sparks from the grinding wheel, is connected by leads 51 and 52 to a relay mechanism 53 which is operated in response to activation of the photo-electric cellv to close a switch connecting a generator 54 to the solenoid 48. One

terminal of the generator 54 is connected by a lead55 to aground 58 and the other terminal of the generator is connected by a lead 57 to the normally open switch in the relay box' 53, the other terminal of said switch being connected by a lead 58 to the solenoid 48 which latter is connected by a lead 60 to a ground., As best shown in Fig. 2, the shield 50 inwhich the photo-electric cell is mounted is carried by a bracket 61 secured to a hood 62 which extends over the workhead, and the opening 63 in the shell 50 is directed toward the incandescent sparks so that the light therefrom may activate the light responsive instrumentality therein to diminish the rate of crossfeed movement.

grinding wheel is withdrawn from the workpiece, the switch in the relay box 53 which has remained closed during the grinding operation is opened and the solenoid 48 is deenergized. A spring 64, which normally tends to rock the bell crank lever 43 clockwise, returns said lever to the positionv shown in Fig. 3, so that the arm 22 is lowered in readiness for a rapid crossfeed movement d a subsequent grinding operation.,

In the operation of the machine. the grindingv wheel is moved axially from the rest position shown in Fig. 1 into the bore of the workpiece substa'n'tially into the position indicated by the dotted lines of Fig. 5 where it is reciprocated axially to procure a traversing movement of the wheel over the workpiece. 'Ihe axial reciprocation procures a rapid crossfeed movement of the grinding wheel perpendicularly to its axis to procure a cutting action between said wheel and workpiece. As the grinding wheel moves into contact light responsive Y. 3 with the worlgiece, incandescent sparksv are given-.pif from e wheelr thereby energizing the element to elevate the armv 22 to diminish the rate of crossfeed movement. As the grinding operation continues, the workpiece is eventually reduced to the predetermined size at which time the grinding wheel is withdrawn axially from the workpiece to the rest position shown and at the same time the crossfeed movement perpendicular to the axis of the grinding wheel is retracted, thereby returning the grind,- ing wheel to the position shown in Fig. 1 in 'readiness for a subsequent grinding operation.

From the foregoing, it will be apparent that the feeding movement of the wheel against the workpiece is procured at a plurality of rates of feed. During the initial movement of the grinding wheel toward the workpiece while said members are still out of contact, the crossfeed movement is rapid-to diminish the unproductive period of the grinding operation. Engagement of the `grinding* wheel with the workpiece produces incandescent sparks which activate alight responsive element for diminishing the rate of feeding movement to a suitable grinding rate. Obviously, the rate of crossfeed subsequently may be again diminished as disclosed in the Coradson Patent No. 1,534,302. above noted. l

The term grinding operation" has been used throughout the specification to include the movements of the machine from the rest position.

shown at which time the grinding wheel is out of contact withv the workpiece and has been withdrawn from the bore thereof into thebore of the feeding mechanism to cause the grinding wheel '20 and workpiece to move toward each other to obtain and maintain grinding contact, and means responsive to engagement between the grinding wheel and the workpiece for diminishing the rate of movement when said grinding wheel engages said workpiece independently ofthe originalsize of the workpiece.

2. In a grinding machine, a grinding wheel and v a workholding member, supporting a workpiece, At the end of the Agrinding operation when the feeding mechanism to cause the grinding wheel and workpiece to .move toward each other to obtain and maintain grinding contact, and means for diminishing the rate of movement when said grinding wheel engages said workpiece, said last means involving-a light responsive member energized by the sparks from the grinding wheel.

3. In a grinding machine, a grinding wheel and a workholding member supporting a lworkpiece, means for feeding the grinding wheel against the surfaceof the' workpiece, and means responsive to engagement between the grinding wheel and the workpiece for diminishing the rate of feeding vmovement when the grinding wheel engages the ywork-piece independentlyof the siz'e of the workpiece.

4. In a grinding machine, a grinding wheel and la workholding member supporting a workpiece,

means for feeding the grinding wheel against the gages the workpiece, said last means involving a light responsive member energized by the sparks from the grinding wheel.

5. In a grinding machine, a grinding wheel and a workholding member supporting a workpiece, means for procuring a feeding movement of the wheel toward and against the surface of the workpiece, and means responsive to engagement vof the grinding wheel with the workpiece for procuring a change in the rate of feeding movement, said last means involving a light responsive member.

6. In a grinding machine, a grinding wheel and a workholding member supporting a workpiece, means for procuring a rapid feeding movementof the wheel toward and against the surface of the. workpiece, and means responsive to engagement of the grinding wheel with the workpiece to dif-- minisli the rate of feeding movement, said lastmentioned means comprising a light responsive member energized byv the illumination of the sparks from the grinding wheel. 7. InnI grinding machine, a grinding wheel and a workholding member supporting a workpiece, feeding'mechanism to cause the grinding wheel' and workpiece to move toward each other to obtain andsmaintain/grindmg contact, and means for diminishing the rate of movement when saidA grinding wheel engages said workpiece, said last means involving alight responsive member energized by the sparks from the grinding wheel, said light responsive member operating independently of the size of the unfinished workpiece;

-8. In a grinding machine, a grinding wheel and a workholding member supporting a workpiece, means to procure a crossfee'd movement of the grinding wheel against the surface 'of the workpiece, andl light responsive means` energized by the illumination of the sparks from the grinding wheel for diminishing the rate ofecrossfeed movement as the grinding wheel engages the' workpiece.

9.l In a grinding machine adapted for the successive reduction of a plurality of workpieces to a predetermined size, a grinding wheel and a workholding member supporting a workpiece, means to procure a grinding operation `on a workpiece, said grinding operation involving a. crossfeed movement of said grinding wheel relative to the workpiece, means operative between successive grinding operations to retracn said crossfeed whereby said grinding wheel is out of engagement with the successive workpiece at the beginning of the successive grinding operation'. and means operable during the grinding operation when the 4 grinding wheel engages the workpiece. and in re sp'onse to engagement therebetween for diminishing the rate of crossfeed movement independently of the size ofthe workpiece. o .i

l0. In 'a grinding machine adapted for the suc- .cessive reduction of a plurality of workpieces to a predetermined size, a grinding wheel and `a workholding member supporting a workpiece,

means to procure a grinding operation on a workpiece, said grinding operation involving a crossv feed movement of said grinding wheel relative` feed whereby `said grinding wheelis outof engagement with the successive workpiece at the beginning of the successive grinding operation` and light responsive means operable during the grinding operation and energized by the illumination *and a workholding member supporting' a workof the sparks from the grinding wheel as said wheel engages theA workpiece for diminishing the rate of crossfeed movement.

11. In` a grinding machine, a grinding wheel andv a workholding member supporting a worklpiece, means for procuring a crossfeed movement of the wheel relative to the surface of the workpiece during the grinding operation, said grinding wheel being out of engagement with the workpiece at .the beginning of the grinding operation,` and light responsive means to vary the rate of crossfeed movement in response to engagement of said wheel with the workpiece.

l12. In a grinding machine, a grinding wheel and ay workholdlng member supporting a work-- piece, means to procure a grinding operation on the workpiece, the grinding wheel being out of engagement with the workpieceat the beginning of the grinding operation, and light responsive means energized by the illumination of the sparks from the grinding wheel when said grinding wheel engages the workpiece for procuring a change in the grinding operation. o 13. Ima grinding machina-a grinding wheel and a wrkholding member supportingl a workpiece, means for feeding. the grinding wheel, against the surface of the workpiece, and means for diminishing the rate of feed when the grinding wheel engages the workpiece, saidlast means involving alight responsive member.

14. Ina grinding machine adapted for the successive reduction of a plurality of Kworkpieces to a predetermined size, a grinding'wheel and a workholding member supporting -a workpiece, means to procure a grinding operation on a workpiece, said grinding operation involving a crossfeed movement of said grinding wheelrelative t0 the workpiece, means operative between successive grinding operations to retract said crossfeed whereby said grinding wheel is outof engagement with thesuccessive workpiece at the beginning of the successive grinding operation, and light responsive means operable during the grinding operation and energized bythe illumination of the sparks from the grinding wheel 120 for controlling the rat'e of crossfeed movement. y

, 15. In grinding machine, a grinding wheel and a lworkholding member supporting a workpiece, means to procure a grinding operation on the 125 workpiece, and light responsive means energized by the illumination of the sparks from the grinding wheel for procuring` a change in the grinding operation. Y

`16. In a grinding machine, a grinding wheel 130 and a workholding member supportingha workpiece, means to procure a grinding operation on the workpiece, 'theI grinding wheel being out of engagement of the workpiece at the beginningy of the grinding operation,and light responsive' means energized by the engagement of said grinding wheel with the workpiece for procuring a change in the grinding operation. l

17. In ac grinding machine, a grinding wheel piece, means to procure a grinding operation on \the workpiece, and light responsive means controlled by the illumination of the sparks" from the grinding' wheel for controlling the progress of the grinding operation.

' HAROLD L. BLOOD. 

